Transcript Cell Division - Cowley's Science Classes

The Cell Cycle
Cell Division in Prokaryotes
Binary Fission: the division of a
prokaryotic cell into two identical
offspring cells
Happens in single celled organisms
bacteria reproduction
Asexual Reproduction
Asexual Reproduction: the production of new offspring
from one parent only
Examples: budding, binary fission, Parthenogenesis
How does Sheldon Reproduce?
advantages of asexual reproduction
Stages of the Cell Cycle
1. G₁(GAP) phase: growth phase, cell grows to a
healthy size
2. S (synthesis) phase: DNA is replicated (copied)
3. G₂ phase: cell grows and prepares for cell
division by making new organelles
4. Mitosis: nucleus divides and each new cell is
identical
G₀ phase: happens when the cell is matures and
needs to exit the cell cycle
Examples: nerve cells
cell checkpoints
Stages of Mitosis
hank mitosis
1. Interphase:
•Cell is in a resting phase,
performing cell functions
•DNA replicates (copies itself)
•Organelles double in number to
prepare for cell division
Stages of Mitosis
2. Prophase:
•DNA condenses into chromosomes
•Centrioles migrate to the poles of
the cell
•The nuclear membrane and
nucleolus disappears
•The Mitotic spindles form
Stages of Mitosis
3. Metaphase (longest Phase)
•Chromosomes line up along the equator of the cell
Stages of Mitosis
4. Anaphase
•Chromatids separate and move to opposite poles of
the cell
Stages of Mitosis
5. Telophase
•Chromosomes unwind and
become chromatin
•The nuclear membrane and the
nucleolus are reformed
•The Mitotic spindle disappears
Stages of Mitosis
6. Cytokinesis
•Cytoplasm divides into 2 new cells
evenly
•The Organelles are divided equally
•The 2 Daughter cells are genetically
identical
•The Cells return to interphase
•cell division
•cell division2
•cell division 3
Control of the Cell Cycle
Checkpoints in the cell cycle:
1. Cell Growth Checkpoint (G₁): if the cell is a healthy
size, proteins stimulate DNA replication
2. DNA synthesis Checkpoint (G₂): enzymes check the
DNA, if it passes inspection it can start mitosis
3. Mitosis Checkpoint: if the cell passes, proteins
trigger mitosis to stop and cytokinesis to begin
cell checkpoints
What happens when control is lost?
Cancer: because of a mutation checkpoints are
skipped and the cell replicates uncontrollably
Causes: viruses, genetics, environmental factors
Stem Cells
Stem cells: unspecialized cells that have the potential
to become any type of cell
Found: in human embryos, some adult cells, umbilical
cord blood
Potential uses:
• Repair injuries of the brain and spinal cord
• Cure diseases (diabetes, cancer)
• Replace organs (liver, heart, kidneys)